I like Vista, and Ultimate is the version to get, but I think the best way to get it is to buy a new PC pre-loaded with it, or to build a fresh new box de-novo with all new components that are Vista certified. SOOOOO many of the problems "vista bashers" have been having are hardware/software compatiblity related; bad or no drivers, devices not recognized or crippled, etc. I built a new PC and installed Vista Ultimate and for the most part haven't had any problems. I was even successful installing it on an laptop I have, but it was also "Vista upgrade certified" so no major issues there.
BUT -> there is a valid discount deal there, you'd be getting the router for a sweet discount, so its up to you. That looks like a nice router and has gotten a ton of good reviews.